Hideo Nishimura of Kakegawa, Japan was photographing the night sky on August 11-12, 2023, when he captured a new comet that now bears his name. Comet C/2023 P1 Nishimura is currently moving past the constellation Gemini the Twins, low in the dawn sky. The comet was hiding under the glare of the sun before Nishimura captured it in his images. It will continue to light up as it gets closer to the sun, putting it within reach of binoculars. But will it be bright enough to see only with the eyes?
Although estimates indicate that the comet could become bright enough to be seen without optical aid, at its peak the comet will be very close to the area of the sky where the sun is located. Thus, the comet will likely be difficult to locate due to glare from the sun or daylight. However, during the last days of August and the first days of September, we still have the opportunity to try to spot the celestial visitor using binoculars, a small telescope or long exposure photos, before it doesn’t get too close to the sun. And of course, we can always hope for an explosion while we are still far from the sun.
The currently observed magnitude is around 9.2, which means people using telescopes in dark skies can spot it. Other observations report that the comet’s tail measures eight minutes of arc. The comet is expected to continue to brighten and its tail to grow as it approaches the sun. The comet will be brightest in September, when it is closest to the sun and Earth.
Comet Nishimura is heading towards the sun
On August 15 and 16, 2023, the comet was already flying past Earth’s orbit as it approached the sun. Comet Nishimura is traveling so fast that it will reach the orbit of Venus in just a few days… by August 27, 2023.
Sky enthusiasts can observe the comet with a small telescope during the remaining days of August (see maps below). It is best to try to observe it now, as it may not survive its passage near the sun. This is due to its extremely close passage to our star. Comet Nishimura will pass closer to the sun than Mercury’s orbit. If it survives until August, Comet Nishimura should become a binocular object in the early mornings of September. Then, observers with a clear view of the east-northeast horizon could get good binocular views of comet C/2023 P1 (Nishimura) around September 10, about 45 minutes before sunrise.
The path of the new comet
With such a new comet, there have not been many sightings and the trajectory is still being defined. On August 21, 2023, NASA/JPL performed new orbital calculations that indicate Comet Nishimura orbits the sun every 202 years, suggesting it is a “local” comet to our solar system. not an interstellar comet.
The closest approaches to Earth and the Sun have also been updated by one day each. The closest approach to Earth will be on September 12, 2023, when the comet passes 78 million miles (125 million km) from Earth. Perihelion – or the closest approach to the sun – will occur on September 17, 2023, passing 27 million miles (43.7 million km) from our star.
Some details may be updated as new observations allow scientists to better refine the comet’s orbit.
Comet Nishimura circles the zodiacal constellations. It will move from Gemini to the constellation Cancer in late August and early September. It will cross Leo in mid-September and then visit Virgo in the second half of September.
What will be the luminosity of the comet?
It is always difficult to estimate the luminosity of a comet because it is very unpredictable. Although Comet Nishimura might be bright enough to see with the naked eye, it might also collapse as it approaches the sun. But here’s an approximation of the comet’s brightness on certain dates and where to find it.
Starwalk estimates the comet will have a magnitude of 4.9 – within naked eye range – on September 11. On the morning of September 11, you can search for the comet before dawn. The first object you will notice in the eastern sky is a crescent moon, followed by nearby bright Venus. The comet will be close to the pair and close to the star Adhafera (Zeta Leonis) in the Sickle of Leo (rear question mark). Keep in mind that sunlight coming from below the horizon will make it incredibly difficult to detect anything in the sky.
The comet’s closest approach to Earth will be on September 12, at 0.85 AU. At this time, the comet changes from being a morning object to an evening one. On September 15, the comet will be just 10 arc minutes from Leo’s second-brightest star, Denebola. But the pair will also be just 12 degrees from the sun, making it difficult to capture them after the sun goes down, before it sets.
Starwalk estimates the comet at magnitude 3.2 at perihelion – when the comet is closest to the sun – on September 17. Again, when the comet is bright and close to the sun, it will be difficult to see because it will be close to the sun. on the dome of our sky as well.
Maps of the new comet C/2023 P1



Say goodbye to Comet Nishimura
As the comet moves away from the sun, its brightness decreases. By mid-October our skies will be farther from the sun (20 degrees), but will become darker. It will also be in daylight or below the horizon most of the time. How long can you follow Nishimura when he comes out?
Conclusion: a new comet, named Nishimura, could be bright enough to be seen with the naked eye in September. Learn how to see it here.
Via NASA
Through MPEC
Via Starwalk
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